Oxide semiconductors are one type of oxide with semiconductor characteristics. Oxide semiconductor thin film transistors (TFTs), as a next-generation of basic electronic material, have drawn the attention of global display technicians. Oxide semiconductor TFTs are one preferred candidate for TFT material configured to drive next-generation displays such as ultra-high definition (UHD) liquid crystal panels (LCDs), organic electroluminescent (EL) panels, and electronic paper.
IGZO is an abbreviation of indium gallium zinc oxide. Amorphous IGZO material is channel layer material used in next-generation of TFT technologies and is one metal oxide panel technology. Carrier mobility of IGZO is 20 to 30 times than carrier mobility of amorphous silicon, thus greatly improving charge-discharge rate of the TFT to a pixel electrode. It has a fast refresh rate and a fast response time and is configured to greatly improve pixel scan rate, such that an ultra-high resolution in TFT LCDs is possible. In addition, IGZO displays have highly energy efficient and are more efficient due to a reduced number of transistors and an increased light transmittance of each pixel.
IGZO-TFT devices are generally divided into several types of electronic shelf labels (ESL), back channel etching (BCE), top gates (TG), etc., ESL and BCE structures, due to a large overlap area between a gate electrode and a source/drain electrode, have large parasitic capacitance, and are not suitable for high resolution OLED panels. IGZO devices with top-gate structures developed in recent years can solve the problem of large parasitic capacitance. However, the current mainstream TG-IGZO TFT devices have a complicated manufacturing process and generally require about seven masks to complete the array substrate process.
In summary, manufacturing methods of TG-IGZO TFT devices in existing technologies are complicated and costs are high.